Abstract: Steady laminar boundary layer flow and heat transfer over a thin longitudinal isothermal circular cylinder moving in a flowing stream has been studied in this paper. The cases in which the cylinder is moving in the same (parallel) or in the opposite (reverse) direction to the free stream are considered. The transformed nonsimilar boundary layer equations are solved numerically using the Keller-box method for some values of the curvature parameter, the Prandtl number and relative velocity parameter. The results show that the velocity and temperature distributions as well as the coefficients of skin friction and the local Nusselt number are appreciably affected by the relative velocity parameter.